ACE34AC04

4K I

VER 1.1

11

Read Operations

The read command is similar to the write command except the 8th read/write bit in address word is set to

“1”. The three read operation modes are described as follows:

(A)

Current Address Read

The EEPROM internal address word counter maintains the last read or write address plus one if the

power supply to the device has not been cut off. To initiate a current address read operation, the

micro-controller issues a START bit and a valid device address word with the read/write bit (8th) set

to “1”. The EEPROM will response with an ACKNOWLEDGE signal on the 9

8-bit data word will then be serially clocked out. The internal address word counter will then

automatically increase by one. The address roll-over during a Read is from the last byte of the last

page to the first byte of the first page of the addressed 2-Kbit (depends on the current SPA setting).

For current address read the micro-controller will not issue an ACKNOWLEDGE signal on the 18th

clock cycle. The micro-controller issues a valid STOP bit after the 18

read operation. The device then returns to STANDBY mode.

(B)

Sequential Read

The sequential read is very similar to current address read. The micro-controller issues a START bit

and a valid device address word with read/write bit (8

an ACKNOWLEDGE signal on the 9th serial clock cycle. An 8-bit data word will then be serially

clocked out. Meanwhile the internally address word counter will then automatically increase by one.

Unlike current address read, the micro-controller sends an ACKNOWLEDGE signal on the 18

cycle signaling the EEPROM device that it wants another byte of data. Upon receiving the

ACKNOWLEDGE signal, the EEPROM will serially clocked out an 8-bit data word based on the

incremented internal address counter. If the micro-controller needs another data, it sends out an

ACKNOWLEDGE signal on the 27

out. This sequential read continues as long as the micro-controller sends an ACKNOWLEDGE signal

after receiving a new data word. When the internal address counter reaches its maximum valid

address, it rolls over to the beginning of the memory array address. Similar to current address read,

the micro-controller can terminate the sequential read by not acknowledging the last data word

received, but sending a STOP bit afterwards instead.